(string-to-number "256")


(format "%dx%d=%d" 3 4 (* 3 4))

(downcase "hEllo wOrld")
(upcase "hello world")


'(1 . 2)
(car nil)


'(?a . 1)
(read "(1 . 2)")

(car '(1 . 2))
(cdr '(1 . 2))

'(1 2 3)
'(1 2 . 3)
(setq a '(1 2 . 3))
(car a)
(cdr a)

'(1 . #1=(2 3 . #1#))

'(1 . (2 . (3 . nil)))


(consp a)
(consp nil)
(listp '(1 . 2))
(listp nil)

(null nil)

(cons 1 2)
(cons 1 '())
(setq foo '(a b))
(cons 'x foo)
;; (cons x foo) error

(push 'x foo)
(push 'y foo)

(setq lsta (list 1 2 3))
(cons 'a lsta)
(append lsta '(x y) '(m n))


(append '(a b) 'c)
(append '(a b) '(c d))


(append [a b c] "cd")

(nth 5 '(1 2 3 4 5))



(defun add (a &rest b)
  (message "a:%s,b:%s" a b)
  )

(add 1)
(add 1 2 3)

(nthcdr 0 '(0 1 2 3))
(last '(0 1  2 3 4) 0)





